Lubrication apparatus of high pressure pump for common rail system

ABSTRACT

A lubrication apparatus of a high pressure pump for a common rail system can improve lubrication performance for a friction portion M1 between a roller 12 and a shoe by supplying a large amount of lubricating fuel, which is supplied from a low pressure pump 24, to the friction portion M1 for a short time.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority of Korean Patent Application Number 10-2012-0147886 filed Dec. 17, 2012, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a lubrication apparatus of a high pressure pump for a common rail system, and more particularly, a lubrication apparatus of a high pressure pump for a common rail system which can improve lubricating performance of a friction portion where a roller and a shoe are in contact.

2. Description of Related Art

A high pressure pump 10 used in common rail systems, as shown in FIGS. 1 and 2, includes a pump housing 11, a roller 12, a shoe 13, and a plunger 14 wherein a shaft chamber 11 a, a roller chamber 11 b, and spring chamber 11 c are connected in the pump housing 11.

A camshaft 21 with a cam 21 a is rotatably disposed in the shaft chamber 11 a, the roller 12 and the shoe 13 are disposed in contact with the cam 21 a in the roller chamber 11 b, and a spring 16 is disposed on a spring seat 15 in the spring chamber 11 c.

The plunger 14 is disposed with one end in contact with the shoe 13 and the other end in a fuel compression chamber 17 positioned between an inlet valve 22 and an outlet valve 23.

The inlet valve 22 is a valve disposed in a fuel passage connected with a low pressure pump 24 and the outlet valve 23 is a valve disposed in a fuel passage connected with a common rail 25.

Therefore, as the cam shaft 21 is rotated by driving an engine, the roller 12 pushes the shoe 13 while rotating in accordance with the lift of the profile of the cam and the plunger 14 is reciprocated by the shoe 13 pushed. Further, low pressure fuel supplied to the fuel compression chamber 17 through the inlet valve 22 by the motion of the plunger 14 is compressed at high pressure and then flows out to the common rail 25 through the outlet valve 23.

Meanwhile, the roller 12 and the shoe 13 are in contact under high pressure, so that the wear is caused by friction and burning and sticking are caused, if excessive, unless a friction portion M1 where the roller 12 and the shoe 13 are in contact is sufficiently lubricated; therefore, the friction portion M1 between the roller 12 and the shoe 13 is usually lubricated with fuel from a low pressure pump 24 to preclude those problems.

That is, in the related art, the friction portion M1 between the roller 12 and the shoe 13 is lubricated by using a first lubrication passage 31 connecting the low pressure pump 24 with the shaft chamber 11 a of the pump housing 11 and a second lubrication passage 32 connecting the shaft chamber 11 a with the spring chamber 11 c, so that the shaft chamber 11 a is filled with the fuel from the low pressure chamber 24 and then the spring chamber 11 c is filled, and thereafter, the fuel is applied to the friction portion M1 between the roller 12 and the shoe 13, thereby lubricating the friction portion M1.

However, there is a defect in the structure of the related art described above in that the lubricating fuel flows a long distance to the friction portion M1 between the roller 12 and the shoe 13, so that the camshaft 21 operates before the friction portion M1 between the roller 12 and the shoe 13 is sufficiently lubricated, and in this case, not only the friction portion M1 between the roller 12 and the shoe 13 under large compressive load is severely worn, but the high pressure pump 10 is broken due to burning and sticking, if excessive.

An exemplar of the prior art is Korean Patent Publication No. 10-2005-0051372

The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

The present invention has been made in an effort to solve the defects described above.

Various aspects of the present invention provide for provide a lubrication apparatus of a high pressure pump for a common rail system which allows sufficient lubrication of a friction portion by reducing the path along which lubricating fuel flows to the friction portion where a roller and a shoe are in contact, prevents wear between the roller and the shoe due to friction by improving lubricating performance on the friction portion between the roller and the shoe, and also improves the performance of a high pressure pump.

Various aspects of the present invention provide for a lubrication apparatus of a high pressure pump for a common rail system including: a first lubrication passage connecting a shaft chamber formed in a pump housing with a low pressure pump in a high pressure pump; and a support lubrication passage with one end connected to the first lubrication passage and the other end connected to a friction portion where a roller and a shoe are in contact.

The apparatus may further include a check valve that is disposed in the support lubrication passage, allows the flow of fuel from the first lubrication passage to the support lubrication passage, and prevents backflow of fuel from the support lubrication passage to the first lubrication passage.

The support lubrication passage may include: a diverging passage that diverges from the first lubrication passage and then extends into the roller; and open passages that are connected with the diverging passage and open to the friction portion.

The check valve may be disposed in the diverging passage.

The diverging passage may be positioned at the rotational center of the roller.

A plurality of open passages may be provided to simultaneously supply a large amount of fuel to the friction portion.

It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are views illustrating a lubrication apparatus of a high pressure pump for a common rail system of the related art.

FIGS. 3, 4 and 5 are views illustrating an exemplary lubrication apparatus of a high pressure pump for a common rail system according to the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

A high pressure pump 10 for a common rail system according to various embodiments of the present invention, as shown in FIGS. 3 to 5, includes a pump housing 11, a roller 12, a shoe 13, and a plunger 14, in which a shaft chamber 11 a, a roller chamber 11 b, and spring chamber 11 c are connected in the pump housing 11.

A camshaft 21 with a cam 21 a is rotatably disposed in the shaft chamber 11 a, the roller 12 and the shoe 13 are disposed in contact with the cam 21 a in the roller chamber 11 b, and a spring 16 is disposed on a spring seat 15 in the spring chamber 11 c.

The plunger 14 is disposed with one end in contact with the shoe 13 and the other end in a fuel compression chamber 17 positioned between an inlet valve 22 and an outlet valve 23.

The inlet valve 22 is a valve disposed in a fuel passage connected with a low pressure pump 24 and the outlet valve 23 is a valve disposed in a fuel passage connected with a common rail 25.

Therefore, as the cam shaft 21 is rotated by driving an engine, the roller 12 pushes the shoe 13 while rotating in accordance with the lift of the profile of the cam and the plunger 14 is reciprocated by the shoe 13 pushed. Further, low pressure fuel supplied to the fuel compression chamber 17 through the inlet valve 22 by the motion of the plunger 14 is compressed at high pressure and then flows out to the common rail 25 through the outlet valve 23.

Meanwhile, the roller 12 and the shoe 13 are in contact under high pressure, so that the wear is caused by friction and burning and sticking are caused, if excessive, unless a friction portion M1 where the roller 12 and the shoe 13 are in contact is sufficiently lubricated; therefore, the friction portion M1 between the roller 12 and the shoe 13 is lubricated with fuel from a low pressure pump 24 to preclude those problems.

That is, the lubricating apparatus of a high pressure pump according to various embodiments of the present invention includes, in a high pressure pump 10, a first lubrication passage 31 connecting the shaft chamber 11 a in the pump housing 11 with a low pressure pump 24, a second lubrication passage 32 connecting the shaft chamber 11 a with the spring chamber 11 c, and a support lubrication passage 33 with one end connected to the first lubrication passage 31 and the other end connected to the friction portion M1 where the roller 12 and the shoe 13 are in contact.

Further, the lubricating apparatus according to various embodiments of the present invention further includes a check valve 34 that is disposed in the support lubrication passage 33, allows the flow of fuel from the first lubrication passage 31 to the support lubrication passage 33, and prevents backflow of fuel from the support lubrication passage 33 to the first lubrication passage 31.

The support lubrication passage 33 is composed of a diverging passage 33 a that diverges from the first lubrication passage 31 and then extends into the roller 12 and open passages 33 b that are connected with the diverging passage 33 a and open to the friction portion M1.

One check valve 34 is disposed at the inlet of the diverging passage 33 a, but if the check valve 34 is disposed at each other open passages 33 b, the number of articles, the cost, and the weight increase.

Further, the diverging passage 33 a may be positioned at the rotational center of the roller 12 for smooth flow of lubricating fuel.

If the diverging passage 33 a is biased to a side from the rotational center of the roller 12, the fuel passing through the diverging passage 33 a is biased to a side by a centrifugal force in rotation of the roller 12, so that resistance is generated in the flow of the fuel flowing to the open passages 33 b from the diverging passage 33 a, and accordingly, the fuel cannot smoothly flow to the open passages 33 b from the diverging passage 33 a.

Further, a plurality of open passages 33 b may be formed in order to simultaneously supply a large amount of fuel to the friction portion M1 in consideration of the durability of the roller 12.

According to various embodiments of the present invention described above, some of the lubricating fuel flowing to the shaft chamber 11 a of the pump housing 11 through the first lubrication passage 31 from the low pressure pump 24 is directly supplied to the friction portion M1 between the roller 12 and the shoe 13 through the support lubrication passage 33.

Therefore, compared with the related art, it is possible to considerably reduce the path of the lubricating fuel supplied to the friction portion M1 between the roller 12 and the shoe 13, to reduce the time taken to lubricate the friction portion M1, and to operate the camshaft 21 after the friction portion M1 is sufficiently lubricated, so that it is possible to prevent wear of the friction portion M1 as much as possible, and accordingly, it is possible to significantly improve the durability of the high pressure pump 10.

Further, the lubricating fuel supplied to the shaft chamber 11 a through the first lubrication passage 31 flows to the spring chamber 11 c through the second lubrication passage 32 after filling the shaft chamber 11 a and the lubricating fuel supplied to the spring chamber 11 c is additionally supplied to the friction portion M1 between the roller 12 and the shoe 13 by rotation of the cam 21 a and the roller, so that lubrication performance for the friction portion M1 between the roller 12 and the shoe 13 is considerably improved.

According to the present invention, as a large amount of lubricating fuel supplied from a low pressure pump is supplied to a friction portion between a roller and a shoe, it is possible to prevent wear of the friction portion as much as possible and to considerably improve the durability of a high pressure pump.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

What is claimed is:
 1. A lubrication apparatus of a high pressure pump for a common rail system, the apparatus comprising: a first lubrication passage connecting a shaft chamber formed in a pump housing with a low pressure pump and a high pressure pump; and a support lubrication passage with one end connected to the first lubrication passage and the other end connected to a friction portion where a roller and a shoe are in contact with each other.
 2. The apparatus of claim 1, further comprising a check valve disposed in the support lubrication passage, allows the flow of fuel from the first lubrication passage to the support lubrication passage, and prevents backflow of fuel from the support lubrication passage to the first lubrication passage.
 3. The apparatus of claim 2, wherein the support lubrication passage includes: a diverging passage that diverges from the first lubrication passage and then extends into the roller; and open passages connected with the diverging passage and open to the friction portion.
 4. The apparatus of claim 2, wherein the check valve is disposed in the diverging passage.
 5. The apparatus of claim 3, wherein the diverging passage is positioned at the rotational center of the roller.
 6. The apparatus of claim 3, wherein a plurality of open passages is provided to simultaneously supply fuel to the friction portion. 